Buffer device with torsion bar actuated brakeshoes

ABSTRACT

A buffer device includes a piston slidingly disposed in a cooperating cylinder so as to be displaceable therein by an energized, reciprocative member. A compression spring and a torsion bar are energized by the piston during displacement with the compression spring absorbing sufficient energy from the member to return it to its normal position, and the torque in the torsion bar being applied to a pair of brakeshoes carried by the piston so as to be actuated thereby against the inside of the cylinder to convert to heat the remaining energy imparted to the piston.

United States Patent Inventor Robert G. DeRaad Garretson, S. Dak. Appl. No. 860,284 Filed Sept. 23, 1969 Patented Sept. 7, 1971 Assignee The United States of America as represented by the Secretary of the Army BUFFER DEVICE WITH TORSION BAR 27l,268;267/9 C, 15l;2l3/22, 24,31,32 R, 37

Primary ExaminerGeorge E. A. Halvosa Anomeys- Harry M. Saragovitz, Edward J. Kelly, Herbert Berl and Albert E. Arnold, Jr.

ABSTRACT: A buffer device includes a piston slidingly disposed in a cooperating cylinder so as to be displaceable therein by an energized, reciprocative member. A compression spring and a torsion bar are energized by the piston during displacement with the compression spring absorbing sufficient energy from the member to return it to its normal position, and the torque in the torsion bar being applied to a pair of brakeshoes carried by the piston so as to be actuated thereby against the inside of the cylinder to convert to heat the remaining energy imparted to the piston.

PATENTEDSEP mu sum 1 or 2 my A ATTORNEYS INVENTOR Rghafi ELUERHHEL Y W Al-14 PAT'ENTED'SEP 1 new suwzmz BUFFER DEVICE WITH TORSION BAR ACTUATED BRAKESHOES BACKGROUND OF THE INVENTION This invention relates to automatic firearms and provides therefor a buffer device for resiliently stopping a reciprocative member and returning it to its normal position to complete an operating cycle.

With most automatic guns, especially those which fire highvelocity rounds that create considerable recoil reaction, buffer devices are required for resiliently stopping an energized reciprocative member without injurious impact and then returning it back to its normal position. Most of the buffer devices used in firearms convert the excess energy applied thereto to heat throughfrictional means with the degree of frictional conversion being determined by the load applied to the buffer.

SUMMARY OF THE INVENTION It is a principal object of this invention to provide, for firearms having a reciprocative member energized by cartridge discharge forces, a buffer device for resiliently stopping the member and returning it to its normal position in which buffer device the degree of frictional conversion of the energy transfered to the buffer device by the member is determined by the linear displacement of the energized member and not by the load applied thereby to the buffer device.

It is another object of this invention to provide such a buffer device in which a coiled compression spring is arranged to absorb sufficient energy from the member during its recoil stroke to return it to its normal position with the remaining energy in the member being converted to heat by a pair of brakeshoes which are carried by the piston and which are actuated radially therein against the interior surface of an inclosing cylinder by the torsion-bar spring according to the torque applied thereto.

It is a further object of this invention to provide for such buffer device actuation by means of a cam follower and cam slot arranged to energize the torsion bar by applying a torque thereto during displacement of the member and according to the design of the cam slot.

Further objects and advantages of the invention will be apparent from the following specification and the accompanying drawings which are for the purpose of illustration only.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a longitudinally cross sectioned view of the buffer device with the piston shown in its normal position;

FIG. 2 is a view similar to Fig. l but showing the piston actuated by the gun member to its retracted position;

FIG. 3 is a view taken along line 33 of Fig. l; and

FIG. 4 is a view taken along line 44 of FIG. I.

DESCRIPTION OF THE PREFERRED EMBODIMENT Shown in the FIGS. is a buffer device 12 arranged so as to be acted upon by a reciprocative gun member 14 which is energized by cartridge discharge force for longitudinal displacement from a forward normal position to a rearward retracted position, which is from left to right in the FIGS. Buffer device 12 functions, as hereinafter described, to resiliently stop member 14 in its retracted position by gradually reducing the energy therein to zero and then returning it to its normal forward position with a reduced force.

Buffer device 12 includes a cylinder 16 which slidingly accommodated a piston 18 and the buffer device is positioned so that the piston is displaceable along the extended axis of movement of reciprocating member 14. Piston 18 is provided with a shaft 20 which projects coaxially therefrom through a mating hole 22 in a bearing 24 which is secured to the front end of cylinder 16. The end of shaft 20 is contactable by member 14 during displacement to a retracted position, thereby displacing piston 18 rearwardly in cylinder l6.

The rear end of cylinder 16 is provided with an annular flange 28 which is of T configuration in cross section and includes an annular inner section 30 that forms an annular shoulder 32 around the inside of the cylinder and an outer section 34 that projects outwardly therefrom. A coiled compression spring 36 is disposed between shoulder 32 and the adjacent end of piston 18 so as to be compressed thereby, when displaced by member 14 in cylinder 16, to absorb a portion of the energy in the member.

A cuplike cap 38 is secured to outer section 34 so as to extend coaxially from cylinder 16 and so as to be rotationally adjustable relative thereto through the cooperation of a plurality of bolts 40 mounted through mating holes in the outer section and elongated slots 42 in the cap.

Piston I8 slidingly accommodates a pair of diametrically opposed brakeshoes 44 which are essentially of sectoral configuration in cross section, as noted in FIG. 3, and which are disposed in mating recesses 46 of similar configuration so as to be radially displaceable therein into and out of contact with inner surface 48 of cylinder 16. Each of the brakeshoes 44 includes a friction unit 50, composed of a suitable composition such as is used in brakeshoes for automobiles, and a metallic shell 52 therefor which encases the friction unit except for face 54 thereof which is contactable with inner surface 48. Face 54 is arcuately formed according to the same radius as inner surface 48 so as to have full contact therewith when pressed thereagainst as hereinafter described.

Shells 52 are each provided with a front surface 56 and a rear surface 58 which is parallel thereto, and a first wall 60 and a second wall 62 which are both tapered inwardly and are contactable with cooperating surfaces 64 and 66 in piston 18 to limit inward displacement of the brakeshoes relative thereto. Second wall 62, as shown in FIG. 3, is shorter than first wall 60, for a purpose to be described hereinafter, and they are connected by a planar base 68. Because of the difference in the lengths of first wall 60 and second wall 62, base 68 is angularly disposed relative to an intersecting diameter of cylinder 16, as shown in FIG. 3,

Brakeshoes are actuated outwardly into frictional contact with inner surface 48 by means of a cam shaft 70. Such cam shaft 70 includes a head 72 which is mounted to a torsion-bar spring and is of elliptical configuration to form a pair of diametrically opposed cam lobes 74 each of which is cammingly contactable with base 68 of one of the brakeshoes. Head 72 is rotatingly received in piston 18 by an axial chamber 73, which has communication with recesses 46 so that cam lobes 74 may extend thereinto for camming contact with brakeshoes therein, and the head is held against longitudinal displacement in the piston by contact of the front and rear sides of the head with surfaces 76 and 78. Head 72 is fixed to the front end of torsion-bar spring 80 which extends rearwardly therefrom through compression spring 36 to terminate in cap 38. A cylindrical support 81, formed on the rear end of torsion-bar spring 80, is slidingly disposed in cap 38 and a pin 82 extends diametrically through the support, as shown in FIG. 4, so that the projection ends form a pair of cam followers 84 which cammingly engage a pair of cooperating cam slots in the cap. Cam slots 86 are designed so as to convert longitudinal movement of torsion-bar spring 80, relative to cap 38, to rotational displacement thereof so as to bias head 72 in a direction that rotates cam lobes 74 toward first walls 60, which is in the counterclockwise direction in FIG. 3, to increase the sections of bases 68 along which the cam lobes are cammingly effective.

When member 14 is energized and driven to its retracted position it contacts the end of shaft 20 to drive piston 18 rearwardly in cylinder 16, The displacement of piston 18 compresses spring 36, which absorbs a portion of the energy im parted to the piston by member 14, and drives cam shaft 70 rearwardly. As cam shaft 70 is moved to the rear, followers 84 move along cam slots 86 causing torsion-bar 80 to be wound and absorb more of the energy imparted to piston 18 by member 14. This biases head 72 for rotation so that lobes 74 thereon act against the respective bases 68 of brakeshoes 44 to cam them brakeshoes against inner surface 48 and convert the remaining energy imparted to piston 18 to heat through the frictional contact of the shoes with the inner surface. The design of cam slots 86 determines the pattern of the frictional conversion of of the remaining energy to heat along the longitudinal displacement of member 14. Metallic shells 52 facilitate the sliding contact of brakeshoes 44 with the ontact areas of piston 18 and the sliding contact of cam lobes 78 with the respective bases 68.

When member 14 is stopped at its retracted position it is immediately returned to its normal position by the energy stored in spring 36 and buffer device 12 is thereby made ready for its next cycle. A resilient bumper 88 is installed in the front face of piston 18 to cushion the impact thereof with bearing 24 when stopped thereby in its forward position.

Wear of face 54 and cam slots 86 can readily be compensated for by adjusting the position of cap 38 on cylinder 16, through the cooperation of bolts 40 with slots 42. Also, by having cap 38, with its cam slots 86, adjustable the amount of energy to be stored in torsion bar 80 and applied to brakeshoes 44 can be readily changed.

I wish it to be understood that I do not desire to be limited to the exact details of construction shown and described, for obvious modification will occur to a person skilled in the art.

What I claim is:

l. A buffer device for resiliently stopping an energized reciprocative member at a retracted position and for returning the member to a normal position comprising a cylinder, an inner surface of said cylinder, a piston slidingly accommodated in said cylinder and disposed for displacement by the member when energized, a coiled compression spring arranged in said cylinder for compression by said piston when displaced by the energized member to absorb a sufficient portion of the energy therefrom for returning said piston to the normal position, a torsion-bar spring arranged to be twisted by said piston during displacement by the energized member to absorb a further portion of the energy therein, and a pair of brakeshoes carried by said piston and disposed for actuation by said torsion-bar spring when energized against said inner surface to convert the remaining energy in the member to heat.

2. The buffer device as defined claim 1 and including means for connecting said torsion-bar spring to said piston for l0ngitudinal displacement therewith and rotational displacement relative thereto, and cam means carried by said torsion-bar spring for actuation thereby when energized against said brakeshoes for displacement thereof against said inner surface.

3. The buffer device as defined in claim 2 including a pin extending through said torsion-bar spring, a pair of cam followers formed by projecting ends of said pin, a cap attached to said cylinder, and a pair of cam slots formed in said cap for cooperatively engaging said cam followers, said cam slots being designed so that said brakeshoes are applied thereby against said inner surface for frictional contact therewith according to the displacement of said piston by the energized member.

4. The buffer device as defined in claim 2, wherein said means for connecting said torsion bar spring to said piston comprises a head of elliptical configuration mounted on one end of said torsion bar spring and cooperating surfaces in said piston, and wherein said cam means on said torsion bar spring comprises a pair of cam lobes formed by the elliptical configuration of said head and disposed for camming contact with said brake shoes.

5. The buffer device as defined in claim 2, and including cooperating cam means attached to said cylinder and to said torsion bar for converting longitudinal displacement thereof by said piston to rotational displacement for energizing said torsion bar spring during displacement thereof by said piston.

6. The buffer device as defined in claim 2, and including a pair of cam followers extending from said torsion bar, a cap mounted on said cylinder, and a pair of cam slots formed in said cap for sliding engagement by said cam followers to translate longitudinal displacement of said torsion bar to rotational displacement thereof.

7. The buffer device as defined in claim 6, and including means for adjustably mounting said cap on said cylinder so as to adjustably compensate for wear of said brake shoes and of said cam slots. 

1. A buffer device for resiliently stopping an energized reciprocative member at a retracted position and for returning the member to a normal position comprising a cylinder, an inner surface of said cylinder, a piston slidingly accommodated in said cylinder and disposed for displacement by the member when energized, a coiled compression spring arranged in said cylinder for compression by said piston when displaced by the energized member to absorb a sufficient portion of the energy therefrom for returning said piston to the normal position, a torsion-bar spring arranged to be twisted by said piston during displacement by the energized member to absorb a further portion of the energy therein, and a pair of brakeshoes carried by said piston and disposed for actuation by said torsion-bar spring when energized against said inner surface to convert the remaining energy in the member to heat.
 2. The buffer device as defined claim 1 and including means for connecting said torsion-bar spring to said piston for longitudinal displacement therewith and rotational displacement relative thereto, and cam means carried by said torsion-bar spring for actuation thereby when energized against said brakeshoes for displacement thereof against said inner surface.
 3. The buffer device as defined in claim 2 including a pin extending Through said torsion-bar spring, a pair of cam followers formed by projecting ends of said pin, a cap attached to said cylinder, and a pair of cam slots formed in said cap for cooperatively engaging said cam followers, said cam slots being designed so that said brakeshoes are applied thereby against said inner surface for frictional contact therewith according to the displacement of said piston by the energized member.
 4. The buffer device as defined in claim 2, wherein said means for connecting said torsion bar spring to said piston comprises a head of elliptical configuration mounted on one end of said torsion bar spring and cooperating surfaces in said piston, and wherein said cam means on said torsion bar spring comprises a pair of cam lobes formed by the elliptical configuration of said head and disposed for camming contact with said brake shoes.
 5. The buffer device as defined in claim 2, and including cooperating cam means attached to said cylinder and to said torsion bar for converting longitudinal displacement thereof by said piston to rotational displacement for energizing said torsion bar spring during displacement thereof by said piston.
 6. The buffer device as defined in claim 2, and including a pair of cam followers extending from said torsion bar, a cap mounted on said cylinder, and a pair of cam slots formed in said cap for sliding engagement by said cam followers to translate longitudinal displacement of said torsion bar to rotational displacement thereof.
 7. The buffer device as defined in claim 6, and including means for adjustably mounting said cap on said cylinder so as to adjustably compensate for wear of said brake shoes and of said cam slots. 